Rotated Subgrids in the FDTD Method

Rotated Nonuniform Subgrids in the FDTD Method With Application to a Hemispherical Antenna Array

“…This algorithm is a direct extension of the method which is explained in detail in [7] so, in this contribution, only the modifications will be described. As in [7], the sub-grid is bounded by two surfaces, the Outer Surface, OS, and the Inner Surface, IS.…”

“…As in [7], the sub-grid is bounded by two surfaces, the Outer Surface, OS, and the Inner Surface, IS. This scheme is shown in Figure 3 for the case where the sub-grid is rotated with respect to the main grid by 30 O .…”

“…More recently, a number of sub-gridding schemes have been proposed to address the analysis of structures which contain fine geometrical detail and which are also electrically large, for instance [3][4] [5][6] [7]. However, these have only been applied to situations where the meshes are uniform and in which the cell size of the sub-grid and the main grid are in a constant integer ratio.…”

“…This is a severe restriction for cases such as an antenna array where each element is, itself, a complicated structure which would be best analyzed using a non-uniform mesh. Moreover, with the exception of [7], the sub-grids are constrained to share the same Cartesian axes as the main grid. For a conformal antenna array, this is another severe restriction.…”

“…In this contribution, the method of [7] is generalized and extended to allow the use of sub-grids which are not only rotated with respect to the main grid but which can also be non-uniform and independent of the size of the cells in the main grid. In Section II the algorithm will be described and then in Section III some results will be presented.…”